UPDATE:  Breaking news :) As of Maya 2012 FBIK will be officially retired. All of the keyframing functionality that worked with FBIK has been integrated into the HIK rig.  So the marking menus for setting key and pose modes, as well as the key/curve filtering in the graphEditor and timeline now work with HIK.

Additionally, going forward HIK will be unified between Maya, MotionBuilder and HIK middleware. The same solver and the same UI are used for both in the 2012 releases.

So everything in this post below refers to pre-2012 releases.

Most of you by now have probably heard of HIK.  But what is HIK exactly?   Frankly, there has been quite a bit of confusion about this because there are actually a few different incarnations out there.  So I figured I'd take a stab at trying to clear things up (as best as they can be cleared up anway).  Ugh... do I really want to open up this can of worms?  OK, what the heck :)

So, in general, when people are talking about HIK they are referrring to a character rigging and animation system.  But... there are actually four implementations (or you might even say versions) of HIK out there.  This can be very confusing to say the least.  It all breaks down as follows...

1. There is the original implementation of HIK (aka FBIK) that exists in MotionBuilder.  This is the core character rigging and animation system inside of MotionBuilder.  It can be used for hand animation (i.e. keyframing), mocap editing, retargeting, clip creation, non-linear animation editing and any number of other things that you can do within MotionBuilder.

2. There is something call FBIK in Maya which is based on HIK. This was the first incarnation of the MotionBuilder rig in Maya. It has been around since version 7.0.  It is essentially an automated full body IK/FK rigging and animation system for characters.  It does not have any associated retargetting or non-linear editing capabilites, and is primarily used for key frame animation.  Here is a demo that I did a while back which shows the basic key framing workflow for the FBIK rig in Maya...

(Quick credit: Thanks to Insomniac studios for the character from the game Resistance: Fall of Man)

It is also interchangable (via FBX) with the rig in MBr and can be transferred back and forth between Maya and MBr.  I did a blog post on this topic last year which you can check out here in you're interested  ->  FBIK interop

Then, to give you an idea of the kinds of things that you can do with the rig in MotionBuilder that you can not do with the rig in Maya, here is a quick demo that I put together of the Story tool in MotionBuilder.  Again this is just one example.

(Quick credit:  Thanks to HighMoon studios for the character from the game DarkWatch)

3. There is the new HIK rig in Maya 2011 which has only been available for a few months. It is intended for retargeting purposes and currently does not replace the keyframing (hand animation) functionality that you have with FBIK in Maya... although as with any feature it will evolve over time.  FBIK and HIK currently co-exist in Maya.  Additionally... HIK in Maya is not intended to replace MotionBuilder...  anyone that is doing large amounts of retargetting and/or mocap editing, or anyone that needs to do non-linear clip editing will still want to use MotionBuilder for these and a variety of other reasons.  However HIK in Maya does provide an option for users who need to do some basic retargetting and don't want to leave Maya.  Here is a general overview of HIK in Maya.

4. There is the middleware component of HIK which has an associated plugin for Maya. This is independent of the standard Maya feature set and is not the same as the HIK retargetting system that is shown above.  HumanIK middleware has become quite popular in the games industry and has been used on a wide array of titles including Ubisoft's Assassin's Creed and the upcoming EA title MMA .  Check out this movie to get an overview of what it is and how it can be used on the engine side

As I mentioned there is a Maya authoring component to this, as well as integration with Unreal.  You can see these in action in a demo from -> GDC

So there you have it... clear as mud right?  Well hopefully it's at least a little less murky than it was before :)

Now, if you've made it this far then you will likely be interested in checking out an upcoming webinar on HumanIK.  At 10 am PST on September 9th Autodesk is sponsoring a webcast with Gamasutra focused on Middleware. Here is a description of the session:

Autodesk and EA Sports present the Game Developer Webcast, featuring a discussion with Simon Sherr, Animation Director for Electronic Arts Tiburon, moderated by Mary Beth Haggarty.

EA Sports MMA heavily leveraged Autodesk® HumanIK® in their production of complex character interaction. In this session we discuss implementation of Human IK features for EA’s Mixed Martial Arts fighting game including: dynamic Footplanting, Non-Uniform Player Scaling, Interaction-based player scale compensation, and partial body “Relative IK” interactions.

Register for the webcast here ->   www.autodesk.com/gamasutrawebcast

Note:  There will also be second Middleware webcast on September 29 featuring Kynapse and Beast.  I will post details for this when they become available.